Willis Mountain is a Kyanite mine in Sprouses Corner, Farmville District, Buckingham Co., Virginia, USA. According to Mindat there are 30 or more valid minerals found in multiple areas on the mountain and around the mountain. Malachite is not one of the listed minerals. I attended a field trip this past weekend hosted by The Gem & Mineral Society of Lynchburg. Many specimens were collected after breaking pieces off the host matrix with a 20 pound sledge hammer. I would have photographed the large boulder had I known that this was not a known mineral found a this site. This is one of 6 specimen I collected.

I will check it using vinegar, it has a hardness between 3 and 4 and leaves a light green streak. On a few of the specimen there are small areas with a deep blue color, possibly azurite. I have not examined most of the specimens closely since coming back from the field trip.

I had the opportunity to visit the geology department at James Madison University, where Dr. Lance Kearns helped identify minerals for members of our mineral club. He could not make a visual identification, so we used XRD and the results left me with a dilemma. XRD came up with Guildite, Koechlinite, and Georgechaoite as possibilities, Dr. Kearns said none of these completely matched the unknown specimen. My understanding is XRD is the most definitive test to identify a mineral, my dilemma is what should I do next to identify this specimen.

XRD is not always going to give you a cut and dry answer. Some minerals have very similar structures (i.e. stilbite and stellerite) and differentiating them by XRD may not be possible, especially since it does not give chemical data. I imagine Dr. Kearns would investigate the mineral next using SEM-EDS, which would provide some information on semi-quantitative chemistry.

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